Art of cracking hydrocarbons



ART OF CRACKING H'YDROCARBONS.

APPLICATION FILED MAR. 22, 1917. RENEWED JUNE 14, 1920.

J. W. COAST Patented Aug. 3, 1920.

- UNITED STATES PATENT orFicE.

JOHN W. COAST, JR., OF TULSA, OKLAHOMA, ASS IGNOR TO THE PROCESSCOMFAIIY, A

CORPORATION OF MARYLAND.

. m or CRACKING 'nYniaocAiiiioi rs.

Application filed JlI-arch 22, 1917, ser al No. 156,646.

0 all whom it may concern:

Be it known that I, J 0111 1 W. COAST, Jr., a citizen of-the UnitedStates of America, a resident of Tulsa, in the county of Tulsa, State-ofOklahoma, have invented certain new and useful Improvements in the Artof Cracking Hydrocarbons, of which the following is a full, clear, andexact description, reference being had to the accompanying drawing,forming a part of this specification.

My invention relates to improvements in the art of crackinghydrocarbons, and more particularly to a method of protecting stillsfrom the injurious effects of coke or tarry,

-ally drop to the bottom of the still and accumulate thereon at pointswhere the still is subjected directly to the action of the intense heat.This coke or carbon is produced partly by heavy fractions in the refluxcondensate and partly by other fractions which do not vaporize in thestill. It prevents the free transmission ofheat from the still bottom tothe liquid contents of the still, and,

when a sufiicient quantity has been accumulated, the still bottombecomes red hot. Some immediate steps must then be taken to avoid arupture at the overheated portion of the still. In actual practice, thecoke accumulates on-the hot still bottom While the oil in the still ismaintained at a high temperature and under a high'pressure, thusrendering the cracking operation quite dangerous. p

The main ObJGCt of 'my invention is to prevent a large body-of the"coke, or tarry coke-formingsubstances, from accumulating in a singlepillata point transmitted to the still; In the preferred form of theinvention, this is accomplished by condensingfthe'high boiling pointfrac;

tions and conducting such condensate to a point Where it Will not besubjected directly to the intense heat at the still bottom. Therelatively heavy coke-forming fractions are Specification of LettersPatent.

Where the heat is Renewed June 14,1920. Serial no, 389,007.

prevented from circulating to the hottest Patented Aug. 3, 192,0.

part of the still, the lighter fractions of the reflux condensate beingpermitted to circulate freely in the liquid contents of the still. Ithuseffect a separation of the lighter hydrocarbons from the cokeforming matter in the reflux 'condensatepermitting the lighterhydrocarbons to be re-vaporized and retaining the coke at apoint Whereit will not interfere withthe transmission of heat through the stillbottom.

Figure I is a diagrammatic View of 4 a crackingapparatus adapted for usein carrying out my'method.

F 1g. II is a transverse-section of the still taken approximately on theline IIII,

Fig. I.

he still 1, arranged above a heating chamber 2, is connected by means ofan air cooled vapor pipe 3 to a reflux condenser 4. 5 designates a vaporpipe leading from the reflux condenser to a main condensing'coil 6 fromwhich the low boiling-point product is recovered. Thecondensing coil 6.is preferably arranged in a 'Water tank 7. 8'designates a return pipefor conducting reflux condensate from the condenser 4 to the still.

-The air-cooled vaper pipe 3 constitutes a reflux condenser, and it isinclined to allow v the-condensate to flow backwardly to the still.

The apparatus I have shown is particularly adapted for use in crackinghigh boiling point products of distillation, such, for example, as thedistillates or residues resulting from the distillation of crudepetroleum. The substances to be treated are introduced into the still inany suitable manner, and any desired pressure may be obtained byregulating a valve 9, preferably located in the vapor pipe 5. Thepressure in the still is preferably greater than 50 pounds per squareinch, and the temperature of the contentsof the still preferably rangesfrom about 600 F. to 800 F. Heat generated in the heating chamber 2 istrans- Initted directly through the still bottom to boilin point vaporspassing from the liquid flow t rough the vapor pipe 3. and refluxcondenser 4: to the pipe 5, leading to the main condenser 6. Therelatively high boiling point fractions are condensed in the vapor pipe3 or in the condenser 4, such fractions being returned either throughthe the liquid contents of the still. The low vapor pipe 3 or returnpipe 8. This reflux condensate includes a large percentage of heavycoke-forming fractions commingled with lighter fractions,'w hich maybei'rediS- tilled toform-part of the low boiling point product.

- In the preferred form of the invention the end portions of the stillbottom are seated upon theJWalls 10 of the heating chamber, and theseWalls protect said end portions from the intense heat of the'heatingchamber. The heat is transmitted directly through the middle portionofthe still bottom, and the protected end portions of the still aremaintainedin a relatively cool conconductors' 12' lead from 1 dition.-,Diverging v a funnel 1,3 to coke pockets 14 at the ends of the stillbottom. The funnel 13 lies directly below reflux condensate ferablyarranged on positively the heat is transmitted tothe still. The coke isthus trapped and confined on the tected' end portions of the stillbottom, where it will not interfere withzthe transstill; The relativelylight fractions of the reflux condensate circulate freely from the cokepockets 14 and. .commingle with the liquid in the still. The co ke inthe pockets ing such hydrocarbons the vapor domeiat the upper portion ofthe still, Where it will receive the discharged from the pipes '3 and 8.Dams, or obstructions, '15 are prethe still bottom to I prevent thevheavy coke-forming fractions from reaching the points at which stillunder pressure,

liquid. contents of still bottom, prov cool end portions, mission ofheat tothe liquid contents of the leis-not materially agitated by thecirculationof the liquid in the still, and owing to its weight-it doesnot tend to float or rise in the lighterliquid- The coke pockets arepreferably formedv belowthe surface of the liquid in the still so as topermit the relatively light fractions to circulate from the coke, andthe conductors l2'are preferably'submerged the hot liquid-so that thereturning condensate will 'be heated before it reaches the coke pockets.Iclaim: v

In the art of cracking petroleum hydro-- carbons, the method whichcomprises confinting heat directly to the middle portion of the'stillbottom, maintaining the. end portions of thestill bottomin a relativelycool condition, maintaining the contents of the conducting vapor fromthe still to a main condenser, also condensing the high boiling pointfractions and' conducting such condensate through the on the relativelycool end portions of the preventing the relatively heavy coke-formingfractions of said condensate from circulatihg away from said relativelyand permitting the lighter fractions of said condensate-tocirculatefreely in the contents of the still.

In testimon that I claim the foregoing I hereunto a x m signature. I aJgHN W. COAST, In.

in a still, transmitthe still anddepositing it

